Perovskite semiconductors have emerged as a promising class of materials for X-ray detection due to their exceptional optoelectronic properties, ease of fabrication, and tunable compositions. Their high atomic number (high-Z) elements, such as lead (Pb) and bismuth (Bi), contribute to strong X-ray attenuation, making them ideal for efficient X-ray photon capture. The performance of perovskite-based X-ray detectors is primarily governed by charge collection efficiency, sensitivity, and noise characteristics, which are intrinsically linked to the material’s electronic and structural properties.

The high-Z nature of perovskite semiconductors is critical for X-ray detection. Materials like methylammonium lead triiodide (MAPbI3) and formamidinium lead triiodide (FAPbI3) contain heavy Pb atoms, which enhance photoelectric absorption of X-rays due to their large cross-sections for interaction with high-energy photons. The attenuation coefficient scales approximately with Z^4/E^3, where Z is the atomic number and E is the X-ray energy. For instance, Pb (Z=82) offers significantly higher X-ray stopping power compared to traditional silicon (Z=14). Bismuth-based perovskites, such as Cs3Bi2I9, also exhibit strong X-ray absorption while mitigating toxicity concerns associated with Pb. The choice of perovskite composition directly influences the detector’s quantum efficiency, with thicker films or single crystals further improving absorption efficiency.

Charge collection efficiency (CCE) is a key metric determining the detector’s performance. CCE depends on the material’s charge carrier mobility-lifetime product (μτ), which quantifies how far photogenerated carriers can travel before recombining. High-quality perovskite single crystals, such as MAPbBr3, have demonstrated μτ products exceeding 10^-2 cm^2/V for electrons and holes, enabling efficient charge extraction. Defect engineering through compositional tuning (e.g., mixed-cation or mixed-halide perovskites) reduces trap densities, thereby enhancing CCE. For example, CsPbBr3 single crystals with low defect densities exhibit near-unity CCE under moderate electric fields, making them suitable for high-resolution X-ray imaging.

Sensitivity, defined as the detector’s current response per unit X-ray dose rate, is another critical parameter. Perovskite detectors achieve high sensitivity due to their large X-ray absorption coefficients and excellent charge transport properties. Reported sensitivities for MAPbI3-based detectors exceed 10^4 μC/Gy·cm^2, outperforming conventional amorphous selenium (a-Se) detectors. The sensitivity is influenced by the applied bias voltage, with higher fields improving charge collection but also increasing dark current. Optimizing the trade-off between sensitivity and noise is essential for practical applications. Strategies such as heterostructure design (e.g., perovskite/organic semiconductor hybrids) have been employed to suppress dark current while maintaining high sensitivity.

Noise characteristics, including shot noise and flicker noise, impact the detector’s signal-to-noise ratio (SNR) and limit the minimum detectable dose. Perovskites with low ion migration tendencies, such as those incorporating cesium (Cs) or formamidinium (FA), exhibit improved stability and reduced noise under prolonged X-ray exposure. The defect-tolerant nature of perovskites also contributes to lower noise compared to traditional semiconductors like CdTe, where deep-level traps dominate noise behavior.

Environmental stability remains a challenge for perovskite X-ray detectors, particularly under high X-ray flux and humidity. Encapsulation techniques and compositional engineering (e.g., introducing hydrophobic ligands or inorganic perovskites like CsPbBr3) have shown promise in enhancing operational stability. Additionally, the scalability of perovskite deposition methods, such as blade-coating or inkjet printing, enables cost-effective fabrication of large-area detectors for medical imaging and security screening.

The following table summarizes key performance metrics for select perovskite X-ray detectors:

Material | μτ Product (cm^2/V) | Sensitivity (μC/Gy·cm^2) | Detection Limit (nGy/s)
MAPbI3 | ~10^-3 | ~2×10^4 | ~50
CsPbBr3 | ~10^-2 | ~3×10^3 | ~100
Cs3Bi2I9 | ~10^-4 | ~1×10^3 | ~200

Future advancements in perovskite X-ray detectors will likely focus on further improving μτ products through defect passivation, exploring lead-free alternatives without compromising performance, and integrating perovskites with readout electronics for real-time imaging applications. The combination of high-Z elements, superior charge transport, and tunable optoelectronic properties positions perovskite semiconductors as a transformative technology for next-generation X-ray detection systems.